Home
Back
Pressure of Dry H2 Formula:
| From: | To: |
The pressure of dry hydrogen gas calculation determines the partial pressure of hydrogen when collected over water. This accounts for the water vapor pressure that contributes to the total measured pressure.
The calculator uses the formula:
Where:
Explanation: When gases are collected over water, the total pressure is the sum of the partial pressure of the dry gas and the vapor pressure of water. Subtracting the water vapor pressure gives the true pressure of the dry gas.
Details: Accurate pressure calculation is crucial for gas law calculations, stoichiometric determinations in chemical reactions, and precise measurement of gas volumes in laboratory settings.
Tips: Enter the total measured pressure and the water vapor pressure at the experimental temperature. Both values must be in Pascals (Pa) and valid (non-negative values).
Q1: Why do we need to subtract water vapor pressure?
A: When gases are collected over water, water vapor contributes to the total pressure. To get the true pressure of the dry gas, we must subtract the water vapor pressure.
Q2: How do I determine water vapor pressure?
A: Water vapor pressure depends on temperature and can be found in standard reference tables or calculated using established formulas based on the experimental temperature.
Q3: What units should I use for pressure?
A: This calculator uses Pascals (Pa), but you can convert from other units (mmHg, atm, etc.) before entering values. 1 atm = 101325 Pa, 1 mmHg = 133.322 Pa.
Q4: Can this calculation be negative?
A: The result should not be negative under normal conditions. If you get a negative value, check that your water vapor pressure isn't higher than your total pressure.
Q5: Is this specific to hydrogen gas?
A: While this calculator is labeled for hydrogen, the same principle applies to any gas collected over water where you need to determine the dry gas pressure.